The invention relates to a permanent-field rotor of an electric machine, an electric machine comprising such a rotor, and a method for mounting at least one permanent magnet on a surface of a rotor of an electric machine.
Such a rotor or method is used respectively in permanent-field wind power generators or the production thereof, for example. In the case of such large-scale electric machines, it is usually necessary to mount and attach multiple magnetized magnets to the rotor of the machine, since subsequent magnetization is not possible. Owing to their high susceptibility to corrosion, the magnets must be protected against environmental conditions such as humidity and aggressive mediums, for example. These requirements are incompatible with cost-effective economical manufacture, particularly in the case of high unit volumes.
The attachment of the magnets was previously achieved by adhesive fixing of the individual magnets, for example, using an additional bandage as a means of securing and protecting the magnets against environmental influences, particularly in the case of internal rotors. It is also customary to adhesively fix or encapsulate the individual magnets in shells, said shells being mounted on carrier plates and the carrier plates attached to the rotor. A plurality of carrier plates per pole are arranged one behind the other in an axial direction. In the case of smaller machines, mounting is customarily effected using pockets into which the magnets are inserted and fixed by adhesion. It is also customary to use magnet covers which are welded onto the rotor base plate, the magnets being then inserted and encapsulated.
EP2410633A1 discloses a rotor arrangement with permanent magnets, said arrangement comprising a rotor, a plurality of non-magnetic profiled tubes and a plurality of permanent magnets. Each of the tubes defines a closed channel in this case, and is attached to the circumference of an outer side of the rotor, the permanent magnets being arranged in the tubes.
AT184978B discloses a magnet wheel for synchronous machines, wherein each permanent magnet pole is equipped with a pole shoe which is supported via adapters against correspondingly shaped poles that are not made of permanently magnetic material, whereby only compressive stresses can occur in the material of the permanent magnetic poles under the effect of centrifugal force.
EP 2 555 383 A1 discloses a permanent magnet arrangement in which permanent magnets are fixed to a rotor by means of a cover, wherein the cover is fixed by means of T-shaped projections which are enclosed by the rotor yoke.
EP 1 990 811 A1 discloses a method and an arrangement for protecting permanent magnets, wherein the permanent magnets and a protective cover are fixed by adhesion to a base plate.
WO 2011/107168 A1 discloses a method for attaching a magnet to a rotor, wherein the magnet is arranged on the surface of the rotor, wherein a pair of retaining elements are arranged on either side of the magnet and the arrangement is evacuated, and wherein an adhesive is used to attach the magnets and the retaining elements to the rotor surface.